Weight Loss Calculator
Estimate your Basal Metabolic Rate (BMR), Total Daily Energy Expenditure (TDEE), and the time it may take to reach your target weight based on your daily calorie intake.
Male
Female
Sedentary (little or no exercise)
Lightly Active (light exercise/sports 1-3 days/week)
Moderately Active (moderate exercise/sports 3-5 days/week)
Very Active (hard exercise/sports 6-7 days a week)
Extremely Active (very hard exercise/physical job)
calories/day
Understanding Weight Loss
Weight loss is fundamentally about creating a calorie deficit, meaning you consume fewer calories than your body burns. This calculator helps you estimate the key metrics involved in this process.
Basal Metabolic Rate (BMR)
Your Basal Metabolic Rate (BMR) is the number of calories your body needs to perform basic, life-sustaining functions while at rest. This includes breathing, circulation, cell production, nutrient processing, and organ function. It's the minimum energy required to keep you alive.
The calculator uses the Mifflin-St Jeor Equation, which is widely considered one of the most accurate BMR formulas:
- Men: (10 × weight in kg) + (6.25 × height in cm) – (5 × age in years) + 5
- Women: (10 × weight in kg) + (6.25 × height in cm) – (5 × age in years) – 161
Total Daily Energy Expenditure (TDEE)
Your Total Daily Energy Expenditure (TDEE) is the total number of calories your body burns in a 24-hour period, including your BMR and the calories burned during physical activity. It's a more realistic estimate of your daily calorie needs.
TDEE is calculated by multiplying your BMR by an activity factor:
- Sedentary: BMR × 1.2 (little or no exercise)
- Lightly Active: BMR × 1.375 (light exercise/sports 1-3 days/week)
- Moderately Active: BMR × 1.55 (moderate exercise/sports 3-5 days/week)
- Very Active: BMR × 1.725 (hard exercise/sports 6-7 days a week)
- Extremely Active: BMR × 1.9 (very hard exercise/physical job)
Calorie Deficit for Weight Loss
To lose weight, you need to consume fewer calories than your TDEE. This creates a calorie deficit, forcing your body to use stored energy (fat) for fuel. Approximately 3,500 calories equals one pound of fat, or about 7,700 calories for one kilogram of fat.
A healthy and sustainable rate of weight loss is typically 1-2 pounds (0.5-1 kg) per week, which corresponds to a daily calorie deficit of 500-1000 calories.
How to Use the Calculator
- Enter your Current Weight and Target Weight: Specify your starting and desired weight, selecting the correct unit (lbs or kg).
- Enter your Height and Age: Provide your height in cm or inches and your age in years.
- Select your Gender: Choose Male or Female, as BMR calculations differ.
- Choose your Activity Level: Select the option that best describes your typical weekly physical activity.
- Enter your Target Daily Calorie Intake: This is the average number of calories you plan to consume per day. If you're unsure, a common starting point for a deficit is TDEE minus 500 calories.
- Click "Calculate Weight Loss": The calculator will then provide your BMR, TDEE, estimated daily calorie deficit, and the projected time to reach your target weight.
Example Calculation
Let's consider a 30-year-old female, 170 cm tall, weighing 70 kg, with a target weight of 60 kg, who is moderately active and aims for a daily intake of 1800 calories.
- BMR: (10 × 70) + (6.25 × 170) – (5 × 30) – 161 = 700 + 1062.5 – 150 – 161 = 1451.5 calories
- TDEE (Moderately Active): 1451.5 × 1.55 = 2249.8 calories
- Weight to Lose: 70 kg – 60 kg = 10 kg
- Total Calorie Deficit Needed: 10 kg × 7700 calories/kg = 77,000 calories
- Actual Daily Calorie Deficit: 2249.8 (TDEE) – 1800 (Target Intake) = 449.8 calories/day
- Estimated Time to Reach Target: 77,000 calories / 449.8 calories/day = ~171.2 days
- In Weeks: 171.2 days / 7 days/week = ~24.5 weeks
- In Months: 24.5 weeks / 4.33 weeks/month = ~5.6 months
This example shows that with a consistent 1800 calorie intake, this individual could reach her target weight in approximately 5 to 6 months.
Important Considerations
This calculator provides an estimate. Actual weight loss can vary due to individual metabolism, adherence to diet, exercise consistency, and other factors. Always consult with a healthcare professional or a registered dietitian before making significant changes to your diet or exercise routine.